Schema v0.938 ...

Fix bug in experimental ONMjs data model editor. I missed an observer registration: address store must watch the data store to catch namespace/component removals. On removal of the selected address from the store, ONMjs.AddressStore sets itself to removed namespace's immediate parent's address. This in turn signals all observers of the stored address that the selection has changed. And finally, the observers of the stored address update themselves _not_ displaying information linked to data that has been removed from the store (the bug).